29. How does Avalung work?
Even if it is compacted, avalanche snow contains a certain amount of air for breathing. Provided your airways are clear, you can breathe this air. However, after a short time, your warm breath forms an airtight cavity in front of your mouth, preventing the carbon dioxide escaping into the surrounding snow. CO2 poisoning quickly follows, ultimately resulting in suffocation.
Avalung is an emergency device intended to help victims breathe under snow. The mouth piece must be inserted into the mouth during the descent. Avalung uses a system of valves to take breathable air from the front of the body, while expelling poisonous CO2 to the back. The idea is to keep the victim breathing in the avalanche and extend the survival time – assuming (a) you have managed to insert the mouthpiece, (b) the enormous weight of snow does not make it impossible to expand the rib cage, and (c) your airways are clear. If your mouth, nose or throat are blocked with snow, it will be virtually impossible to breathe through the snorkel. The Avalung is worn over the clothing with a support system. However, Avalung does not prevent burial and cannot reduce the burial depth. In other words you will still need your companions to rescue you.